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    Mathematical modeling of a slurry bubble column reactor for hydrodesulfurization of diesel fuel: Single- and two-bubble configurations

    , Article Chemical Engineering Research and Design ; Volume 100 , August , 2015 , Pages 362-376 ; 02638762 (ISSN) Khadem Hamedani, B ; Yaghmaei, S ; Fattahi, M ; Mashayekhan, S ; Hosseini Ardali, S. M ; Sharif University of Technology
    Institution of Chemical Engineers  2015
    Abstract
    In this investigation, a mathematical model for HDS of diesel fuel in a slurry bubble column reactor was developed. The model is based on the axial dispersion of the heterogeneous gas flow regime, which includes two various bubble classes: large (20±70mm) and small (1±10mm). By assuming only large or large plus small bubbles in the column, single- and two-bubble class mode equations are developed. The developed models to solving the mass and enthalpy balances from which the sulfur conversion was obtained that undertaken. The chemical kinetics over NiMoS/γ-Al2O3 catalyst were undertaken for the reaction rate of the involved reactions. The reactor operating conditions... 

    Application of multi-speed gearbox in infinitely variable transmission

    , Article Iranian Journal of Science and Technology - Transactions of Mechanical Engineering ; Volume 41, Issue 2 , 2017 , Pages 149-157 ; 22286187 (ISSN) Khadem Nahvi, M ; Delkhosh, M ; Foumani, M. S ; Rostami, P ; Sharif University of Technology
    Shiraz University  2017
    Abstract
    One way to reduce vehicles' fuel consumption (FC) is to optimize different parts of its powertrain. Among different modern powertrains, continuously variable transmission (CVT) is one of the common types which changes speed ratio between engine and wheels, continuously. Therefore, the CVT allows the engine to operate at its fuel-optimal speed. Due to the limited power transmission capacity and speed ratio range of the CVT, researchers attempted to combine the CVT with a planetary gear train and a fixed ratio mechanism. This mechanism is called infinitely variable transmission (IVT). In this study, a multi-speed gearbox (MSG) is used in the IVT and its impact on the powertrain performance and... 

    Comments on "non-linear free vibration analysis of a string under bending moment effects using the perturbation method"

    , Article Journal of Sound and Vibration ; Volume 285, Issue 1-2 , 2005 , Pages 511-512 ; 0022460X (ISSN) Navazi, H. M ; Ghorashi, M ; Khadem, S. E ; Rezaee, M ; Sharif University of Technology
    Academic Press  2005

    Mass transfer through PDMS/zeolite 4A MMMs for hydrogen separation: Molecular dynamics and grand canonical Monte Carlo simulations

    , Article International Communications in Heat and Mass Transfer ; Volume 108 , 2019 ; 07351933 (ISSN) Riasat Harami, H ; Amirkhani, F ; Khadem, S. A ; Rezakazemi, M ; Asghari, M ; Shirazian, S ; Sharif University of Technology
    Elsevier Ltd  2019
    Abstract
    In industry, utilizing membrane separation technology to purify natural gas streams is of remarkable significance. Molecular Simulation was used in the current article to study the structural and gas separation properties of polydimethylsiloxane (PDMS)/zeolite 4A Mixed Matrix Membranes (MMMs). To explore the optimal performance of MMMs, several structural analyses, namely Fractional Free Volume (FFV), Radial Distribution Function (RDF), X-Ray Diffraction (XRD) and also Glass Transition Temperature (Tg) as one of the most important properties of membranes have been evaluated. Also, the solubilities and diffusivities of periodic cells were respectively measured using MSD and adsorption... 

    Development of systematic framework for an intelligent decision support system in gas transmission network

    , Article Industrial and Engineering Chemistry Research ; Volume 54, Issue 43 , 2015 , Pages 10768-10786 ; 08885885 (ISSN) Khadem, S. A ; Bozorgmehry Boozarjomehry, R ; Sharif University of Technology
    American Chemical Society  2015
    Abstract
    In a gas transmission network (GTN), faults can easily propagate due to the interconnections of streams. The main objective of this paper is to develop a systematic framework for an online decision support system (DSS) in order to make the right decisions to get the GTN out of critical conditions (which cannot be handled by the plant controllers) smoothly. One of the key features of the proposed scheme is its lack of dependence on prior knowledge of the fault signals (e.g., number of faults, and their origin). In this article, the GTN is modeled by a fuzzy directed graph (FDG). The proposed approach utilizes a reasoning algorithm based on the deviations that exist in the process variables... 

    Investigating the effect of engine noise on power management strategy of a hybrid electric vehicle

    , Article Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering ; Volume 232, Issue 10 , 2018 , Pages 1287-1296 ; 09544070 (ISSN) Delkhosh, M ; Aliramezani, M ; Khadem Nahvi, M ; Sharif University of Technology
    SAGE Publications Ltd  2018
    Abstract
    Hybrid electric vehicles (HEVs) have been developed as a promising way to decrease the fuel consumption and emissions of conventional vehicles. Although the noise emission of HEVs is generally lower than that of conventional vehicles, it is still an issue, especially in urban transportation. In this paper, a power management strategy is developed to minimize the annoying noise of the engine for an HEV. This is a modified version of the strategy that was originally established based on the speed ratio of continuously variable transmission (CVT) as the control parameter (CVT-based strategy). The engine combustion noise is assessed using the experimental data of the in-cylinder pressure. Also,... 

    A modular force-controlled robotic instrument for minimally invasive surgery – efficacy for being used in autonomous grasping against a variable pull force

    , Article International Journal of Medical Robotics and Computer Assisted Surgery ; Volume 12, Issue 4 , 2016 , Pages 620-633 ; 14785951 (ISSN) Khadem, S. M ; Behzadipour, S ; Mirbagheri, A ; Farahmand, F ; Sharif University of Technology
    John Wiley and Sons Ltd  2016
    Abstract
    Background: Many deficiencies of minimally invasive robotic surgery systems can be eliminated by using automated laparoscopic tools with force measurement and control capability. Method: A fully modular, automated laparoscopic instrument with a proximal force sensory system was designed and fabricated. The efficacy of the instrument was evaluated experimentally when functioning in an autonomous force-controlled grasping scheme. Results: The designed instrument was shown to work easily with standard laparoscopic tools, with the whole distal part detachable for autoclave sterilization. The root mean squared error (RMSE) of the actual pinch force from the target ramp was 0.318 N; it was 0.402 N... 

    Pressure and temperature functionality of paraffin-carbon dioxide interfacial tension using genetic programming and dimension analysis (GPDA) method

    , Article Journal of Natural Gas Science and Engineering ; Volume 20 , September , 2014 , Pages 407-413 ; ISSN: 18755100 Khadem, S. A ; Jahromi, I. R ; Zolghadr, A ; Ayatollahi, S ; Sharif University of Technology
    2014
    Abstract
    A precise semi-empirical correlation for the calculation of interfacial tension (IFT) between the carbon dioxide and paraffin group to be used in an enhanced oil recovery process and the chemical industry is introduced. Genetic programming and dimension analysis (GPDA) are combined to create a correlation for the calculation of the equilibrium interfacial tension of the carbon dioxide and paraffin group, based on the explicit functionality of the pressure and temperature. The parameters of the correlation consist of critical temperature, critical pressure, density of paraffin at normal temperature, and diffusion coefficients. The pool of experimental data for developing the correlation... 

    QuT: A low-power optical network-on-chip

    , Article Proceedings - 2014 8th IEEE/ACM International Symposium on Networks-on-Chip, NoCS 2014, 17 September 2014 through 19 September 2014 ; 2015 , Pages 80-87 ; 9781479953479 (ISBN) Khadem Hamedani, P ; Enright Jerger, N ; Hessabi, S ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2015
    Abstract
    To enable the adoption of optical Networks-on-Chip (NoCs) and allow them to scale to large systems, they must be designed to consume less power and energy. Therefore, optical NoCs must use a small number of wavelengths, avoid excessive insertion loss and reduce the number of microring resonators. We propose the Quartern Topology (QuT), a novel low-power all-optical NoC. We also propose a deterministic wavelength routing algorithm based on Wavelength Division Multiplexing that allows us to reduce the number of wavelengths and microring resonators in optical routers. The key advantages of QuT network are simplicity and lower power consumption. We compare QuT against three alternative... 

    Error correction in pitch detection using a deep learning based classification

    , Article IEEE/ACM Transactions on Audio Speech and Language Processing ; Volume 28 , 2020 , Pages 990-999 Khadem Hosseini, M ; Ghaemmaghami, S ; Abtahi, A ; Gazor, S ; Marvasti, F ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2020
    Abstract
    While pitch detection has been the focal subject of numerous research efforts for several decades, it is still a challenging task in noisy conditions. In this article, we propose a method to improve the pitch detection accuracy of conventional pitch detection methods. The proposed pitch detection process starts with using the pitch value estimated by a conventional pitch detection method. Then, it extracts pitch candidates according to the most probable types of errors in the initial estimation of high-pitch and low-pitch frames classified by a Deep Convolutional Neural Network (DCNN). Next, a restrained selection procedure is run to find the true pitch value from the set of pitch... 

    Quantum dots for photocatalysis: synthesis and environmental applications

    , Article Green Chemistry ; Volume 23, Issue 14 , 2021 , Pages 4931-4954 ; 14639262 (ISSN) Jouyandeh, M ; Mousavi Khadem, S ; Habibzadeh, S ; Esmaeili, A ; Abida, O ; Vatanpour, V ; Rabiee, N ; Bagherzadeh, M ; Iravani, S ; Saeb, M. R ; Varma, Rajender. S ; Sharif University of Technology
    Royal Society of Chemistry  2021
    Abstract
    Quantum dots (QDs) with unique properties have been widely employed for energy, environmental, and health care applications. Green natural resources, because of their renewability, sustainability, abundance, low cost, and environmental-friendliness, can be utilized for the synthesis of diverse nanoarchitectures. This critical review highlights the recent advancements in the greener and sustainable synthesis of carbon, graphene and metal-based QDs, as well as their significant environmental applications such as photocatalytic hydrogen production, degradation of hazardous contaminants/pollutants and reduction of CO2, with emphasis on the important challenges and future perspectives. © The... 

    Improved algorithms in parallel evaluation of large cryptographic S-boxes

    , Article International Journal of Parallel, Emergent and Distributed Systems ; Volume 35, Issue 4 , 2020 , Pages 461-472 Khadem, B ; Ghasemi, R ; Sharif University of Technology
    Taylor and Francis Ltd  2020
    Abstract
    Nowadays computational complexity of fast Walsh Hadamard transform and non-linearity for Boolean functions and large cryptographic substitution boxes is a major challenge of modern cryptography research on strengthening encryption schemes against linear and differential attacks. Time and memory complexities of the best existing algorithm for computing fast Walsh Hadamard transform and non-linearity for (Formula presented.) substitution boxes is (Formula presented.). This paper proposes three new innovation in acceleration methods that improve the computation time for paralleled Walsh matrix up to 68 folds and the evaluation time for non-linearity degree up to 1021 folds. These methods... 

    A novel cnn-lstm model for predicting the railway sector stock price in the tehran stock exchange

    , Article 2023 9th International Conference on Web Research, ICWR 2023 ; 2023 , Pages 108-114 ; 979-835039969-1 (ISBN) Bodaghi, F ; Owhadi, A ; Nasr, A. K ; Khadem sameni, M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2023
    Abstract
    As a country's financing arm, the capital market can play a crucial role in long-term projects and be responsible for large-scale financing. While the development of rail transport has exceptionally positive and significant effects on the country's macroeconomy, and investment in this sector leads to the prosperity of other economic sectors, the return on investment may be delayed or unclear. Consequently, this uncertainty diminishes the investment appeal in this field. Thus, predicting the price and future value of railway company stocks on the stock market is vital due to the need for the foresight to take safe investment measures and achieve sustainable financing. To this end, this paper... 

    Recent advances in aqueous virus removal technologies

    , Article Chemosphere ; Volume 305 , 2022 ; 00456535 (ISSN) Al-Hazmi, H. E ; Shokrani, H ; Shokrani, A ; Jabbour, K ; Abida, O ; Mousavi Khadem, S. S ; Habibzadeh, S ; Sonawane, S. H ; Saeb, M. R ; Bonilla-Petriciolet, A ; Badawi, M ; Sharif University of Technology
    Elsevier Ltd  2022
    Abstract
    The COVID-19 outbreak has triggered a massive research, but still urgent detection and treatment of this virus seems a public concern. The spread of viruses in aqueous environments underlined efficient virus treatment processes as a hot challenge. This review critically and comprehensively enables identifying and classifying advanced biochemical, membrane-based and disinfection processes for effective treatment of virus-contaminated water and wastewater. Understanding the functions of individual and combined/multi-stage processes in terms of manufacturing and economical parameters makes this contribution a different story from available review papers. Moreover, this review discusses... 

    Hyperbranched polyethylenimine functionalized silica/polysulfone nanocomposite membranes for water purification

    , Article Chemosphere ; Volume 290 , 2022 ; 00456535 (ISSN) Vatanpour, V ; Jouyandeh, M ; Akhi, H ; Mousavi Khadem, S. S ; Ganjali, M. R ; Moradi, H ; Mirsadeghi, S ; Badiei, A ; Esmaeili, A ; Rabiee, N ; Habibzadeh, S ; Koyuncu, I ; Nouranian, S ; Formela, K ; Saeb, M. R ; Sharif University of Technology
    Elsevier Ltd  2022
    Abstract
    Hyperbranched polyethyleneimine functionalized silica (PEI-SiO2) nanoparticles with considerable hydrophilicity were synthesized and incorporated into a polysulfone (PSF)/dimethylacetamide (DMA)/polyvinylpyrrolidone (PVP) membrane casting solution in five different ratios to fabricate PEI-SiO2/PSF nanocomposite membranes using nonsolvent-induced phase separation. The hydrophilic PEI-SiO2 nanoparticles were characterized by TEM, FTIR, TGA, and XPS analyses. Morphology, water contact angles, mean pore sizes, overall porosity, tensile strengths, water flux, antifouling and the dye separation performances of the PEI-SiO2/PSF membranes were also studied. The PEI-SiO2 nanoparticles were uniformly... 

    Adsorption onto zeolites: molecular perspective

    , Article Chemical Papers ; Volume 75, Issue 12 , 2021 , Pages 6217-6239 ; 03666352 (ISSN) Salmankhani, A ; Mousavi Khadem, S. S ; Seidi, F ; Hamed Mashhadzadeh, A ; Zarrintaj, P ; Habibzadeh, S ; Mohaddespour, A ; Rabiee, N ; Lima, E. C ; Shokouhimehr, M ; Varma, R. S ; Saeb, M. R ; Sharif University of Technology
    Springer Science and Business Media Deutschland GmbH  2021
    Abstract
    2D minerals are among key elements of advanced systems, but the need for understanding their interactions/reactions with materials and systems in which they are involved necessitates tracking their molecular and atomic monitoring. Zeolitic structures are microporous materials formed in the nature through volcanic activities or synthesis. Because of their outstanding physicochemical properties like cation exchange capacity and excellent adsorption properties, zeolites have found application in diverse chemical processes, e.g., gas adsorption, water purification, and wastewater treatment. Prediction of zeolite performance for a targeted application saves time and expense as such projection... 

    Highly antifouling polymer-nanoparticle-nanoparticle/polymer hybrid membranes

    , Article Science of the Total Environment ; Volume 810 , 2022 ; 00489697 (ISSN) Vatanpour, V ; Jouyandeh, M ; Mousavi Khadem, S. S ; Paziresh, S ; Dehghan, A ; Ganjali, M. R ; Moradi, H ; Mirsadeghi, S ; Badiei, A ; Munir, M. T ; Mohaddespour, A ; Rabiee, N ; Habibzadeh, S ; Mashhadzadeh, A. H ; Nouranian, S ; Formela, K ; Saeb, M. R ; Sharif University of Technology
    Elsevier B.V  2022
    Abstract
    We introduce highly antifouling Polymer-Nanoparticle-Nanoparticle/Polymer (PNNP) hybrid membranes as multi-functional materials for versatile purification of wastewater. Nitrogen-rich polyethylenimine (PEI)-functionalized halloysite nanotube (HNT-SiO2-PEI) nanoparticles were developed and embedded in polyvinyl chloride (PVC) membranes for protein and dye filtration. Bulk and surface characteristics of the resulting HNT-SiO2-PEI nanocomposites were determined using Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and thermogravimetric analysis (TGA). Moreover, microstructure and... 

    Design and prototype of an active assistive exoskeletal robot for rehabilitation of elbow and wrist

    , Article Scientia Iranica ; Volume 23, Issue 3 , 2016 , Pages 998-1005 ; 10263098 (ISSN) Mohammadi, E ; Zohoor, H ; Khadem, S.M ; Sharif University of Technology
    Sharif University of Technology  2016
    Abstract
    Due to the increasing number of people suffering from physical disabilities in the elbow and wrist, developing an assistive wearable robot seems crucial. These disabilities are mostly common in elderly people and people who are suffering from spinal injury or stroke. In this paper, a wearable assistive robot for rehabilitation of the wrist and elbow is developed. The mechanism has 3 Degree of Freedom (DoF); two active DoF for assisting the exion/extension of the elbow and wrist, and a passive one in order to have unconstrained supination/pronation of the forearm. The motors and sensors were chosen based on kinematic constraints governing the motion of arms and wrists. Finally, with the... 

    Development of an Intelligent Decision Support System to Operate Gas Transmission Network

    , M.Sc. Thesis Sharif University of Technology Khadem, Ahmad (Author) ; Bozorgmehry Boozarjomehry, Ramin (Supervisor)
    Abstract
    In plant-wide systems, faults can easily propagate due to the interconnection of streams. The main objective of this paper is to develop a systematic framework for online decision support system (DSS) in order to make the right decision to get the process out of critical conditions (which cannot be handled by the plant controllers) smoothly. One of the key features of the proposed approach is its lack of dependence on prior knowledge of the fault signals (e.g. number of faults, and their origin). In the proposed scheme, the plant is modeled by a fuzzy directed graph (FDG). The proposed scheme utilizes a backward reasoning based on the deviations that exists in the process variables... 

    Optimal Control of a Robotic System Using Deep Reinforcement Learning

    , M.Sc. Thesis Sharif University of Technology Khadem Haqiqiyan, Behrad (Author) ; Sayyaadi, Hassan (Supervisor)
    Abstract
    Robots were designed to aid humans in tasks that were repetitive and/or dangerous. Classical robotic control methods (such as PIDs) show little adaptability in difficult tasks. Deep reinforcement learning is a machine learning approach for finding an optimized agent via trial and error. This research explores the application of deep reinforcement learning (DRL) algorithms to perform a pick and place task with a robotic arm attached to a moving platform. The study focuses on the use of state-of-the-art RL algorithms, including Truncated Quantile Critics (TQC) and Hindsight Experience Replay (HER), to train an agent in a simulated environment. The paper discusses the robotic environment, the...